North Carolina Sen. Kay Hagan raised over $2 million in the second quarter of this year, swelling the Democrat’s war chest ahead of what’s expected to be a challenging reelection campaign, according to campaign officials.

Hagan ended the month of June with $4.2 million in the bank.

The first-term senator is one of a number of Democratic incumbents facing competitive 2014 elections, who have made the most this year of the fundraising head start they have over potential challengers. She previously raised $1.6 million between January and March.

In a statement, Hagan campaign manager Preston Elliott said her fundraising performance reflected “grassroots excitement” for the senator’s future.

“Kay’s broad base of support highlights that North Carolinians value her tireless work on issues from supporting a North Carolina-first economic recovery to keeping student loans affordable to standing up for servicemembers and veterans,” Elliott said.

The Republican field in North Carolina is still taking shape. State House Speaker Thom Tillis has declared a run against Hagan, and his campaign told National Journal this week that he finished last month with about a quarter-million dollars in the bank.

A list of other Republicans are eyeing the race, including Rep. Renee Ellmers, state Senate President Phil Berger, former Ambassador to Denmark Jim Cain and Baptist minister Mark Harris.

The Democratic firm Public Policy Polling released a North Carolina Senate survey last month showing Hagan leading her Republican challengers, but with her own numbers hovering in the mid-40s, signaling that she is likely to have a real fight on her hands.

Hagan’s campaign has treated Tillis as its most significant opponent so far, and the state Democratic Party released a memo Thursday charging that he “has had a rough start to his campaign.”